Firstly, memcache and memcached are different php extensions which written by different groups and both uses memcached service. While memcached extension providing more modern interface to interact with the memcached, it requires libmemcached library which doesn't fully supported on windows. This is why that official extension doesn't exist for windows.
You need to try to find a compiled version of libmemcached which fits your computer's architecture or compile your own (probably it will hard and tricky) or go with memcache extension instead of memcache"d" on windows
Environment (especially windows) specific tricky problems like this is main reason of why i'm using mac (and linux) for quite some time. There are lot of SO questions, mailing/forum threads, github issues about this subject:
When should I use Memcache instead of Memcached?
http://github.com/php-memcached-dev/php-memcached/issues/71
http://www.couchbase.com/forums/thread/libmemcacheddll-32-bit-and-64-bit-php-extensions